1. Field
The present invention relates to a system and method for analyzing rolling stock wheels. The present invention more specifically relates to a system and method involving multiple cameras and lighting for measuring the profiles of such wheels.
2. Related Art
The rolling stock of a railroad, such as box cars, flat cars, tanker cars, hopper cars, gondolas, piggy back carriers for semi-tractor trailers and/or containers, passenger cars, and the like, are subject to wear, fatigue and the like. This is especially true of the wheels and trucks of such rolling stock. Accordingly, it is typically necessary or desirable to inspect such rolling stock, and especially the trucks and wheels of such rolling stock, on occasion to insure that the rolling stock remains safe to use and is not likely to experience a breakdown in the interval between the current inspection and the next inspection of that piece of rolling stock.
Traditionally, such inspections were performed manually. Not only was such manual inspection time consuming and expensive, it was difficult to insure that a given piece of rolling stock was inspected on any reasonable schedule.
Accordingly, as set forth in U.S. Pat. Nos. 6,911,914; 6,909,514; 6,872,945; 6,823,242; 6,768,551; 5,793,492; 5,677,533; 5,596,203; 5,448,072; 5,247,338; 3,253,140; and 3,206,596, each of which is incorporated herein by reference for its teachings, over the last thirty years, various systems and methods have been developed for automatically inspecting various aspects and parameters of railway rolling stock, such as railroad wheel and bearing temperatures, hot rail car surfaces, wheel profiles, and the like. Conventionally, such systems and methods have used passive sensors that generate a 1-dimensional, time-varying signal as the piece of rolling stock passes by the sensor. To provide additional dimensional information, multiple sensors can be arranged either along or perpendicular to the railway rail. More recently, optical-based systems that generate 2-dimensional images of various components of railway rolling stock, such as wheels, truck assemblies, car bodies of the rolling stock and the like, have been used to inspect such rolling stock.
Some optical-based systems provide for laser-based rolling stock wheel profile measuring systems. Such systems (often installed way side) typically derive wheel profile measurements by projecting laser lines onto a surface of the wheel and then capturing an image of the wheel surface with the laser line projected onto it. However, such known systems do not realize certain advantageous features (and/or combinations of features).
For example, the accuracy of measurements obtained using such laser systems is highly dependent on the calibration of the systems. Even minor changes in the setup and/or calibration may not be detectable immediately, therefore increasing the risk of unreliable data. Visual review or other manual processing of an object captured in the image is difficult because any image obtained using such systems is directed primarily to a projected laser line on the object, rather than an image of the object itself. As a result, any such processing is difficult, unreliable and has reduced value. For example, known systems typically derive certain wheel parameters (such as wheel hollowing) by assumption because the wheel parameter may not be clearly seen in images captured by such systems.
Such known systems often require correct calibration of the object to be measured. If the actual object being measured differs from the object that was calibrated, then errors are likely. Further, rolling stock wheels typically vary in size. Such variation typically requires interpolation and/or extrapolation, which may introduce errors.
The apparatus of such systems is typically subjected to vibration from passing rolling stock. Large vibrations may result in movement including relative movement between the laser line and the optical center of the image capturing apparatus. Such vibration and movements can lead to or result in errors.
Further, the laser line(s) of such known systems intended to overlay parent material of the rolling stock wheel may instead overlay foreign materials that are not part of the wheel (e.g. grease on the flanges from lubricators, etc.). Because typical processing algorithms assume that the laser line overlays only the parent material of the wheel, foreign material may negatively affect the accuracy and reliability of any measurements obtained from such systems.
The lasers of such known systems also present a potential safety hazard. While such systems typically include protective measures in the event of a system failure, such protective measures cannot eliminate the risk of laser exposure.
It would be desirable to provide a system, method or the like for capturing, measuring and/or analyzing rolling stock wheel parameters of the type disclosed in the present application that includes any one or more of these or other advantageous features: a system and/or method that does not substantially depend upon detailed calibration of the system or of the object to be measured; a system and/or method that is affected little by foreign materials that are not part of the original rolling stock wheel; a system and/or method that does not utilize lasers and thereby eliminates the risks of exposure to such lasers; and a system and/or method that does not need to derive wheel parameters by assumption but instead may accurately measure complete wheel parameters including wheel hollowing.
Such systems and methods for capturing, measuring and/or analyzing rolling stock wheel parameters would be advantageous for a number of reasons. These reasons include allowing the systems, or inspection stations that utilize such systems, to be located at points where most rolling stock is likely to be inspected at reasonable intervals, such as the entrances or exits to rail yards, without having to significantly involve railroad personnel in the actual inspection. Furthermore, such systems and methods are designed to inspect the rolling stock at speed. That is, the inspection can occur while the rolling stock moves at its normal rate of travel past the inspection station. In contrast, manual inspections typically require the rolling stock to be stopped to allow the railway personnel access to the various components to make the measurements. By allowing the rolling stock to move at speed through the inspection station, the inspection can occur without substantially negatively affecting the schedule of a particular train, thus reducing the cost of the inspection and delays in transporting goods.
Additionally, such systems and methods would avoid several limitations and/or disadvantages of laser-based systems and/or are inherently safer than laser-based systems.